Statistics, spreadsheets: using inverse normal on Google Sheets

Tutoring statistics, normal and inverse normal are common functions related to the normal distribution. The tutor mentions inverse normal, aka inverse normal cdf.

The following is according to my understanding.

In my post from yesterday I mention using the normal cumulative distribution function, aka normal cdf, etc. It’s used to find the proportion of a population that’s less than or equal to a certain value.

Yet, the opposite question can arise: what value separates the population so that a certain proportion is less than or equal to it? In such a case, one will be using what might be called the inverse normal distribution function, the inverse normal cumulative distribution function, inverse normal cdf, inverse norm, etc. It’s referred to in many ways.

An example might be as follows: suppose the mean number of cups of coffee sold at a breakfast counter is 155, with standard deviation 30. What will be their number sold on the bottom 35 percent of mornings?

To use the inverse normal cdf on Google Sheets to answer the above problem, one might proceed as follows:

1. Find the Σ symbol bottom right of the menu area: click it, then select Statistical.
2. Select NORMINV.
3. In the cell, complete the function input: =NORMINV(0.35, 155, 30).

4. The answer, it seems, should be 143.44, rounded to 143.
5. The answer means that, 35 percent of mornings, they will sell 143 or less cups of coffee.

Interesting, eh?

Source:

support.google.com: NORMINV